cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A210391 Number A(n,k) of semistandard Young tableaux over all partitions of n with maximal element <= k; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 3, 4, 1, 0, 1, 4, 9, 6, 1, 0, 1, 5, 16, 19, 9, 1, 0, 1, 6, 25, 44, 39, 12, 1, 0, 1, 7, 36, 85, 116, 69, 16, 1, 0, 1, 8, 49, 146, 275, 260, 119, 20, 1, 0, 1, 9, 64, 231, 561, 751, 560, 189, 25, 1, 0
Offset: 0

Views

Author

Alois P. Heinz, Mar 20 2012

Keywords

Examples

			Square array A(n,k) begins:
  1,  1,   1,   1,   1,    1,    1, ...
  0,  1,   2,   3,   4,    5,    6, ...
  0,  1,   4,   9,  16,   25,   36, ...
  0,  1,   6,  19,  44,   85,  146, ...
  0,  1,   9,  39, 116,  275,  561, ...
  0,  1,  12,  69, 260,  751, 1812, ...
  0,  1,  16, 119, 560, 1955, 5552, ...
		

Crossrefs

Columns k=0-8 give: A000007, A000012, A002620(n+2), A038163, A054498, A181477, A181478, A181479, A181480.
Main diagonal gives: A209673.

Programs

  • Maple
    # First program:
    h:= (l, k)-> mul(mul((k+j-i)/(1+l[i] -j +add(`if`(l[t]>=j, 1, 0)
                     , t=i+1..nops(l))), j=1..l[i]), i=1..nops(l)):
    g:= proc(n, i, k, l)
          `if`(n=0, h(l, k), `if`(i<1, 0, g(n, i-1, k, l)+
          `if`(i>n, 0, g(n-i, i, k, [l[], i]))))
        end:
    A:= (n, k)-> `if`(n=0, 1, g(n, n, k, [])):
    seq(seq(A(n, d-n), n=0..d), d=0..12);
    # second program:
    gf:= k-> 1/((1-x)^k*(1-x^2)^(k*(k-1)/2)):
    A:= (n, k)-> coeff(series(gf(k), x, n+1), x, n):
    seq(seq(A(n, d-n), n=0..d), d=0..12);
  • Mathematica
    (* First program: *)
    h[l_, k_] := Product[Product[(k+j-i)/(1+l[[i]]-j + Sum[If[l[[t]] >= j, 1, 0], {t, i+1, Length[l]}]), {j, 1, l[[i]]}], {i, 1, Length[l]}]; g [n_, i_, k_, l_] := If[n == 0, h[l, k], If[i < 1, 0, g[n, i-1, k, l] + If[i > n, 0, g[n-i, i, k, Append[l, i]]]]]; a[n_, k_] := If[n == 0, 1, g[n, n, k, {}]]; Table[Table[a[n, d-n], {n, 0, d}], {d, 0, 12}] // Flatten
    (* second program: *)
    gf[k_] := 1/((1-x)^k*(1-x^2)^(k*(k-1)/2)); a[n_, k_] := Coefficient[Series[gf[k], {x, 0, n+1}], x, n]; Table[Table[a[n, d-n], {n, 0, d}], {d, 0, 12}] // Flatten (* Jean-François Alcover, Dec 09 2013, translated from Maple *)

Formula

G.f. of column k: 1/((1-x)^k*(1-x^2)^(k*(k-1)/2)).
A(n,k) = Sum_{i=0..k} C(k,i) * A138177(n,k-i). - Alois P. Heinz, Apr 06 2015

A181478 a(n) has generating function 1/((1-x)^k*(1-x^2)^(k*(k-1)/2)) for k=6.

Original entry on oeis.org

1, 6, 36, 146, 561, 1812, 5552, 15372, 40677, 100562, 239316, 541926, 1188341, 2507736, 5149056, 10251560, 19935135, 37790610, 70187260, 127580310, 227779695, 399218820, 688680720, 1169024220, 1956567795, 3228473430, 5260188780, 8462889330, 13461037155
Offset: 0

Views

Author

Wouter Meeussen, Oct 24 2010

Keywords

Crossrefs

Cf. A181477.
Column k=6 of A210391. - Alois P. Heinz, Mar 22 2012

Programs

  • Mathematica
    CoefficientList[Series[1/(1-x)^6/(1-x^2)^15,{x,0,30}],x]

A181479 a(n) has generating function 1/((1-x)^k*(1-x^2)^(k*(k-1)/2)) for k=7.

Original entry on oeis.org

1, 7, 49, 231, 1029, 3843, 13573, 43219, 131131, 370909, 1007083, 2596573, 6466159, 15465961, 35906959, 80682553, 176682268, 376497604, 784435036, 1596836164, 3186750028, 6232957588, 11978020684, 22615355476, 42031123204, 76900938268, 138714560068, 246728568604
Offset: 0

Views

Author

Wouter Meeussen, Oct 24 2010

Keywords

Crossrefs

Cf. A181477.
Column k=7 of A210391. - Alois P. Heinz, Mar 22 2012

Programs

  • Mathematica
    CoefficientList[Series[1/(1-x)^7/(1-x^2)^21,{x,0,30}],x]

A181480 a(n) has generating function 1/((1-x)^k*(1-x^2)^(k*(k-1)/2)) for k=8.

Original entry on oeis.org

1, 8, 64, 344, 1744, 7400, 29632, 106808, 366088, 1168008, 3570240, 10347864, 28915056, 77493096, 201249216, 505130808, 1233655332, 2927916264, 6784208704, 15338678264, 33950726992, 73557910088, 156378379456, 326236930136, 669101503096, 1349416997864
Offset: 0

Views

Author

Wouter Meeussen, Oct 24 2010

Keywords

Comments

a(n-1,k) is conjectured to also be the count of monomials (or terms) in the Schur polynomials of k variables and degree n, summed over all partitions of n in at most k parts (zero-padded to length k).

Crossrefs

For k=2 (two variables): A002620, k=3: A038163, k=4: A054498, k=5: A181477, k=6: A181478, k=7: A181479.
Column k=8 of A210391. - Alois P. Heinz, Mar 22 2012

Programs

  • Mathematica
    CoefficientList[Series[1/(1-x)^8/(1-x^2)^28,{x,0,25}],x]
Showing 1-4 of 4 results.